In accordance with USPS practice, reductions are granted in postage charges for batches of mail when more than a specific number of mail pieces are directed to a particular three or five digit zip code. As shown in U.S. Pat. No. 5,104,681 for a Method and Apparatus for Marking Letter Mail, issued Apr. 14, 1992 to Ronald P. Sansone and assigned to the assignee of the present invention, it is known in the art to print marks on the edge of certain pieces of mail that indicate a zip code break, i.e., the location in a serially processed group of mail pieces at which the zip code changes. However, the addition of indicating marks detract from the appearance of the mailpiece. It is accordingly an object of the invention to provide indicating means to the operator collecting mail pieces from a stacker to indicate separate groups of mail pieces including, but not limited to, those mail pieces which are sealed or unsealed, different mailing jobs, or changes in the zip code.